JUKI lbh-1790 series Engineer's Manual page 51

1. Removing the timing belt
1) Remove the feed plate and the throat plate connection and loosen two setscrews 1 in the hook
driving shaft bearing bush.
2) Tilt the machine head to the side and remove hook sleeve 2.
3) Loosen setscrew 4 in hook driving shaft bearing support 3 and draw backward the hook driving
shaft unit.
4) Loosen two setscrews 6 in intermediate sprocket shaft 5 and draw backward intermediate sprocket
shaft 5.
5) Draw out timing belt 8 from intermediate sprocket 7.
2. Assembling the timing belt
1) Set timing belt 8 to intermediate sprocket 7 and fix intermediate sprocket 7 with two screws.
2) Insert the hook driving shaft to the machine bed and assemble so that timing belt 8 is put on hook
driving shaft sprocket 9. (Be careful that timing belt 8 is not damaged.)
3) Slightly close the bearing play so that there is no longitudinal play at hook driving shaft !0 and fix
setscrew 4 in hook driving shaft bearing support 3. (Press the hook driving shaft unit to the front
side and lightly press hook driving shaft bearing support 3 to the front side in the state that the
flange section of hook driving shaft intermediate bearing !1 comes in contact with the machined
plane of the machine bed.)
4) Raise the machine head and fix two setscrews in hook driving shaft bearing bush !2 . (There is one
flat section on hook driving shaft !0 . Fix screw No. 1 to the flat section.)
(Caution)
1. When asembling timing belt 8, be sure to turn the sewing machine several times by hand
and check that timing belt 8 is not put on one side.)
2. If two setscrews 1 in the hook driving shaft front bearing bush and setscrew 4 in hook
driving shaft bearing support 3 are loosened, the hook vibrates and thread breakage or
stitch skipping will be caused.
Procedures of disassembling/assembling
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